The present invention relates to a novel phthalocyanine crystal, a process for producing the phthalocyanine crystal, an electrophotographic photosensitive member using the phthalocyanine crystal, and a process cartridge and an electrophotographic apparatus including the photosensitive member.
As photoconductor materials for electrophotographic photosensitive members, inorganic photoconductors, such as cadmium sulfide, and zinc oxide, have been conventionally used. On the other hand, organic photoconductors, such as polyvinyl carbazole, oxadiazole, azo pigments and phthalocyanine have advantages of non-pollution characteristic and high productivity compared with the inorganic photoconductors but generally have a low conductivity so that the commercialization thereof has been difficult. For this reason, various sensitizing methods have been proposed, and among them, the use of a unction separation-type photosensitive member including a charge generation layer and a charge transport layer in a laminated state has become predominant and has been commercialized.
On the other hand, in recent years, non-impact-type printers utilizing electrophotography have come into wide in place of conventional impact-type printers as terminal printers. Such non-impact-type printers principally comprise laser beam printers using laser light as exposure light, and as the light source thereof, semiconductor lasers have been predominantly used, in view of the cost and apparatus size thereof. The semiconductor lasers principally used currently have an oscillating wavelength in a long wavelength region of 650-820 nm, so that electrophotographic photosensitive members having a sufficient sensitivity in such a long wavelength region have been developed.
Phthalocyanine compounds are very effective charge generating materials having a sensitivity up to such a long wavelength region, and compared with conventional phthalocyanine compounds and polyvinyl carbazole, oxytitanium phthalocyanine and gallium phthalocyanine are known to have better sensitivities, and various crystal forms thereof have been disclosed, e.g., in Japanese Laid-Open Patent Application (JP-A) 61-239248, JP-A 61-217050, JP-A 62-67094, JP-A 63-218768, JP-A 64-17066, JP-A 5-98181, JP-A 5-263007 and JP-A 10-67946.
Further, it has been known that a phthalocyanine compound of even a similar crystal form can exhibit remarkably different electrophotographic performances, particularly in sensitivity and chargeability, when used in an electrophotographic photosensitive member depending on production process factors, such as starting materials and solvents, and production conditions, such as reaction temperatures and starting material charging ratios.
Production processes for gallium phthalocyanine crystals have been disclosed in, e.g., JP-A 8-100134, JP-A 9-111148, JP-A 9-124967, JP-A 10-7927 and JP-A 10-17784. Further, JP-A 7-331107 discloses a hydroxygallium phthalocyanine crystal containing a polar solvent, such as N,N-dimethylformamide. Electrophotographic photosensitive members using these gallium phthalocyanine crystals are liable to exhibit a fluctuation in electrophotographic performances depending on production lots and do not necessarily have satisfactory sensitivity, potential stability in repetitive use and chargeability in view of requirements for higher speed and higher image quality in electrophotography in recent years.
Further, while having an excellent sensitivity to long-wavelength region, an electrophotographic photosensitive member using a phthalocyanine compound is accompanied with difficulties, such as fluctuation in electrophotographic performances depending on production lots and liability of image defect (sometimes called xe2x80x9cblack spotsxe2x80x9d), that is, black spotty fog occurring in a white background region in a reversal development system, due to local charge injection, particularly in a high temperature/high humidity environment. Further, the photosensitive member is accompanied with a difficulty that its light-part potential is liable to be fluctuated on repetitive use.
In view of the above-mentioned problems of the prior art, a principal object of the present invention is to provide an electrophotographic photosensitive member exhibiting a high-sensitivity characteristic particularly in a semiconductor wavelength region, exhibiting a stable potential characteristic on repetitive used and capable of reducing image defects, particularly backspots in a reversal development scheme.
A further object of the present invention is to provide a novel phthalocyanine crystal capable of providing such a photosensitive member and a process for producing the phthalocyanine crystal.
A still further object of the present invention is to provide a process cartridge and an electrophotographic apparatus including the photosensitive member.
According to the present invention, there is provided a phthalocyanine crystal, comprising: a phthalocyanine compound and a substituted or unsubstituted condensed polycyclic hydrocarbon compound.
The present invention further provides some processes for producing the above-mentioned phthalocyanine crystal.
The present invention also provides an electrophotographic photosensitive member comprising a support, and a photosensitive layer disposed on the support and containing the above-mentioned phthalocyanine crystal.
The present invention further provides a process cartridge and an electrophotographic apparatus respectively including the above-mentioned electrophotographic photosensitive member.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.